1. Field of the Invention
The present invention relates to gas filtration, specifically to filtration systems for filtration of gas by spraying liquid.
2. Description of the Related Art
In many industries, there exists the problem of removing suspended particulates from a stream of gas which is to be vented to the atmosphere. For example, spent gases from combustion or drying installations, ventilation gases from dusty workshops, and waste gases from heavy organic basic chemistry are frequently loaded with soot, dust, or other harmful particles. Furthermore, stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as the Earth's ecosystems. In addition, air pollution is often the cause of respiratory disease, and, in some instances, death. Therefore, it is desirable to remove particulates from the vented gases prior to discharge to avoid atmospheric pollution.
Gas filtration is very common in industry, and usually aims to at least partially eliminate solid particles from the gas stream. As a result, various designs of different types of filtering equipment have been developed to remove pollutants, and other particulates from gas. The various approaches to filtration may generally be categorized as “wet” or “dry.” With dry methods, particulate matter in a gas stream is removed by physical separation. This is ordinarily effected through the use of filters, electrostatic precipitators, or centrifugal separators such as cyclones. While dry methods of separation have several desirable attributes, they have no utility in removing vapors or gaseous contaminants from a gas stream.
Wet separation methods, on the other hand, can be used to remove various gaseous and vaporous impurities, as well as solid materials from a gas stream. In particular, where acidic gaseous and vaporous impurities are present, the gas stream is often brought into contact with a liquid solution or slurry. During wet separation, a liquid solution, usually constituted of a water slurry bearing a basic reactant such as crushed limestone, is brought into intimate contact with a gas stream, such as by spraying. By vigorously intermixing the gas stream with the liquid solution, it is possible to react the liquid solution with the acidic impurity to produce a neutral product that is carried from the gas stream by the entraining liquid solution. Furthermore, a liquid solution is often intermixed with a gas stream to carry pollutants away from the gas stream for future filtration. Some improvements have been made in the field. Examples of references related to the present invention are described below, and the supported teachings of each reference are incorporated by reference herein:
U.S. Pat. No. 4,144,040, issued to Claes et al., discloses a method and apparatus for demisting gases wherein a stream of gas containing submicron liquid particles is caused to pass through a filter material comprising at least in part a material having a porosity of at least 0.985.
U.S. Pat. No. 6,733,575, issued to Lefever et al., discloses a a coal-fired power generation system including means for the production of coal-derived gas and a filter system for the filtration of this coal-derived gas. The filter system comprises at least one high temperature and, corrosion resistant filter. The filter is made from a Fe—Cr—Al based alloy further comprising at least one additional element selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta and the lanthanides.
U.S. Pat. No. 5,421,846, issued to Klimczak, discloses an air filtration apparatus for industrial applications is disclosed, which includes a front vertical wall which can be positioned to form one side of a work station. The interior of the housing is divided between an upper dirty air chamber which receives the contaminated air from the work station, and a lower clean air chamber. The dividing wall between the two chambers is in the form of a transverse panel which is inclined with respect to the horizontal, and a plurality of hollow pedestals extend upwardly from the transverse panel. Cartridge type filters are mounted upon the pedestals, with the open ends of the filters facing downwardly and being pressed against the pedestals by hand operated clamps so as to form a seal therebetween. A reverse pulse air cleaning system is also provided, which periodically injects a pulse of air upwardly into the lower open end of each of the filters, so as to periodically clean the collected particulates from the outer surfaces of the filters. The removed particles then drop onto the inclined transverse panel and slide therealong toward to the front vertical wall of the housing, where they may be readily removed.
U.S. Pat. No. 5,064,454, issued to Pittman, discloses an apparatus for the removal of asbestos or other matter from a gas stream in a conduit is disclosed. The apparatus includes at least two filter units installed in parallel to receive and filter the gas stream from the conduit, outlets for solid matter at the bottom of each filter unit, and first and second valves respectively on either side of each filter unit for isolating each filter unit for cleaning by compressed air jets when desired. Preferably, the apparatus includes a displacement chamber upstream of the filter units, with much of the asbestos being removed from the bottom thereof. The outlets at the bottom of each filter unit and the collecting and discharge area at the bottom of the displacement chamber are sealed from the surrounding environment, and the filtered solid matter is discharged into bags via at least one bagging unit sealed to the outlets and the discharge area. Preferably, third valves are provided at the solid matter outlet of each filter unit, and these outlets are connected back to the displacement chamber via a return conduit. Fourth valves from the filter unit are connected to a higher pressure gas source, such as the atmosphere in a vacuum system, so that the solid matter may be routed back to the displacement chamber by closing the first and second valves and opening the third and fourth valves.
U.S. Pat. No. 3,966,434, issued to Frazier, discloses a process for removing solids from a stream of gas comprising passing a solids-laden gas through a woven fabric filter bag, which bag is installed with longitudinal slack, wherein, during filtration, the differential pressure across the bag causes the bag to expand outwardly. During clean-off, the exhaust valve of the apparatus is closed and, as the differential pressure across the bag approaches zero, the bag becomes slack and the solids deposited on the filter surface disengage therefrom and drop, by gravity flow, to a collection bin. The exhaust valve is then opened and the step of removing solids from the gas stream is resumed.
U.S. Pat. No. 3,057,137, issued to Perlis et al., discloses a gas cleaning apparatus comprising, a pair of spaced elongated sectioned housings, filter elements in each section of said housings, an elongated inlet duct means located intermediate of and coextensive with said housings, said inlet duct means having an opening at one end thereof connectible to a source of gas to be cleaned and having a first plurality of openings communicating with said filter elements in said sectioned housings respectively, said inlet duct being progressively reduced in cross sectional area from said opening connectible to a source of gas to be cleaned to the other end thereof, elongated outlet duct means located intermediate of and coextensive with said housings, said outlet duct having an opening at one end thereof connectible to a suction means and a second plurality of lateral openings spaced longitudinally, said second plurality of openings in said outlet duct communicating with a third plurality of longitudinally spaced openings in said housings respectively, and said outlet duct being progressively reduced in cross sectional area from said opening connectible to said suction means to the other end thereof.
U.S. Pat. No. 6,962,615, issued to Staudenmayer et al., discloses a filter element composed of a nonwoven filter web of metal fibers affixed to a support body, in which the metal fibers of the filter web form an unsintered composite having a porosity of at least 90%. Preferably the metal fibers have a diameter of at most 4 .mu.m.
However, previous filtration devices and systems suffer from a number of disadvantages, which include: being expensive, being difficult to use, being ineffective, being inefficient, being difficult to handle, not being adaptable, being incapable of withstanding high temperatures, and/or being incapable of withstanding high pressures.
Accordingly, there exists a need for a filtration system that solves one or more of the problems herein described or that may come to the attention of one skilled in the art after becoming familiar with this specification